1. Field of the Invention
The present invention relates to an article transferring device and an article transferring method for transferring articles by using a robot.
2. Description of the Related Art
It is known to provide a system in which a vision sensor detects a plurality of articles being conveyed on a conveyor and, based on position information of each detected article, a robot holds the article while following the conveying motion of the conveyor and transfers the article to another place.
Japanese Unexamined Patent Publication No. H08-063214 (JPH08-063214A), for example, discloses a visual tracking method in which a vision sensor detects workpiece being conveyed on a conveyor and, based on the position of the detected workpiece, a robot holds the workpiece while following the conveyor. In this visual tracking method, the conveyor is equipped with a pulse coder in order to detect the amount by which the workpiece has been conveyed. Upon recognizing from the output signal of the pulse coder that the workpiece has been conveyed a predetermined distance, the visual sensor obtains an image of the workpiece being conveyed. Upon recognizing from the output signal of the pulse coder that the workpiece has been conveyed the predetermined distance, the tracking motion of the robot is started under the control of a robot controller. During the tracking motion, the robot controller controls the robot in a tracking coordinate system moving with the workpiece and causes the robot to hold the workpiece being conveyed on the conveyor by considering the position of the workpiece obtained from the image obtained by the vision sensor.